Giant reversible elongation upon cooling and contraction upon heating for a crosslinked cis poly(1,4-butadiene) system at temperatures below zero Celsius

Lu, Lu; Cao, Jinbao; Li, Guoqiang

doi:10.1038/s41598-018-32436-9

Cited by 31 publications

(18 citation statements)

References 36 publications

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“…As seen in Table 3, a stronger loading force generated a larger instantaneous elasticity coefficient k1 which was accompanied by a larger retarded elasticity coefficient k2. These results were consistent with findings from related studies [32,33]. Additionally, the series viscous coefficient c1 and parallel viscous coefficient c2 were also greater.…”

Section: Single-factor Experiments Analysis and Discussionsupporting

confidence: 93%

Creep Modelling of Rootstock during Holding in Watermelon Grafting

Lou

et al. 2021

Agriculture

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The fragile structure of a rootstock predisposes the stem to mechanical damage during grafting. Thus, it is necessary to take into account the rootstock’s rheological properties under mechanical compression when designing a clamping mechanism. This study focused on cucurbit, a typical rootstock for watermelon grafting. Firstly, we adopted a four-element Burgers model to analyze viscoelastic behavior and deformation characteristics of the rootstock, then conducted creep tests to obtain the parameters of the viscoelastic model. Next, we developed a model for the rootstock during holding based on viscoelastic parameters, loading force and contact time. Moreover, we evaluated the effect of various loading forces and test velocities on creep deformation to reveal the least damage on the rootstock. Results showed that the influence of loading force on the creep deformation was greater than test velocity. Finally, the holding test indicated that the clamping mechanism with silicone rubber can effectively prevent the damage to the stem. Specifically, the loading force should be controlled below 4 N to reduce the associated damage. Taken together, our findings provide a theoretical basis for analyzing the holding damage mechanism during watermelon grafting.

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Section: Single-factor Experiments Analysis and Discussionsupporting

confidence: 93%

Creep Modelling of Rootstock during Holding in Watermelon Grafting

Lou

et al. 2021

Agriculture

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“…The design of the gripper was chosen so that one In the beginning, the development of strain over time exhibited a strong drop in strain (Figure 8a), which was attributed to the melting of highly oriented PDA crystals. In particular, in the first five cycles, the actuation showed a drop (Figure 8b), which was presumably caused by rearrangements of polymer chains [55]. A more stable actuation was then observed; after about 25 cycles of heating and cooling, the actuation was nearly the same.…”

Section: Resultsmentioning

confidence: 94%

Actuating Shape Memory Polymer for Thermoresponsive Soft Robotic Gripper and Programmable Materials

et al. 2021

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For soft robotics and programmable metamaterials, novel approaches are required enabling the design of highly integrated thermoresponsive actuating systems. In the concept presented here, the necessary functional component was obtained by polymer syntheses. First, poly(1,10-decylene adipate) diol (PDA) with a number average molecular weight Mn of 3290 g·mol−1 was synthesized from 1,10-decanediol and adipic acid. Afterward, the PDA was brought to reaction with 4,4′-diphenylmethane diisocyanate and 1,4-butanediol. The resulting polyester urethane (PEU) was processed to the filament, and samples were additively manufactured by fused-filament fabrication. After thermomechanical treatment, the PEU reliably actuated under stress-free conditions by expanding on cooling and shrinking on heating with a maximum thermoreversible strain of 16.1%. Actuation stabilized at 12.2%, as verified in a measurement comprising 100 heating-cooling cycles. By adding an actuator element to a gripper system, a hen’s egg could be picked up, safely transported and deposited. Finally, one actuator element each was built into two types of unit cells for programmable materials, thus enabling the design of temperature-dependent behavior. The approaches are expected to open up new opportunities, e.g., in the fields of soft robotics and shape morphing.

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“…In the following, employing the experiments reported by Lu et al (2018b), which studied the material under both compressive and tensile loading and by applying an optimization procedure, material parameters of the model are calibrated and presented in Table 3. Subsequently, the bending behavior of a cantilever beam is conducted.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…For instance, shape memory poly(e-caprolactone)-co-poly(ethylene glycol) foams which could be ultraviolet (UV) cured and exhibited reversible actuation when compressed was proposed by Baker et al (2013). A new two-way SMP was fabricated by Lu et al (2018b), with cross-linked cis poly(1,4-butadiene) that can be actuated below 0°C with giant actuation strain under both tensile and compression loading condition. Hui et al (2020) fabricated a porous SMP foam with a two-way SME and conducting some tests under constant compression.…”

Section: Introductionmentioning

confidence: 99%

Developing a beam formulation for semi-crystalline two-way shape memory polymers

Maleki-Bigdeli

Baniassadi

Wang

et al. 2020

Journal of Intelligent Material Systems and Structures

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In this research, the bending of a two-way shape memory polymer beam is examined implementing a one-dimensional phenomenological macroscopic constitutive model into Euler–Bernoulli and von-Karman beam theories. Since bending loading is a fundamental problem in engineering applications, a combination of bending problem and two-way shape memory effect capable of switching between two temporary shapes can be used in different applications, for example, thermally activated sensors and actuators. Shape memory polymers as a branch of soft materials can undergo large deformation. Hence, Euler–Bernoulli beam theory does not apply to the bending of a shape memory polymer beam where moderate rotations may occur. To overcome this limitation, von-Karman beam theory accounting for the mid-plane stretching as well as moderate rotations can be employed. To investigate the difference between the two beam theories, the deflection and rotating angles of a shape memory polymer cantilever beam are analyzed under small and moderate deflections and rotations. A semi-analytical approach is used to inspect Euler–Bernoulli beam theory, while finite-element method is employed to study von-Karman beam theory. In the following, a smart structure is analyzed using a prepared user-defined subroutine, VUMAT, in finite-element package, ABAQUS/EXPLICIT. Utilizing generated user-defined subroutine, smart structures composed of shape memory polymer material can be analyzed under complex loading circumstances through the two-way shape memory effect.

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Giant reversible elongation upon cooling and contraction upon heating for a crosslinked cis poly(1,4-butadiene) system at temperatures below zero Celsius

Cited by 31 publications

References 36 publications

Creep Modelling of Rootstock during Holding in Watermelon Grafting

Creep Modelling of Rootstock during Holding in Watermelon Grafting

Actuating Shape Memory Polymer for Thermoresponsive Soft Robotic Gripper and Programmable Materials

Developing a beam formulation for semi-crystalline two-way shape memory polymers

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